1. Field of the Invention
The present invention relates to an image signal processing apparatus, and, more particularly, to an image signal processing apparatus that detects the position of a specific part of an object.
2. Description of the Related Art
In reading information on an original or a document as image signals (image data) using an image scanner, the image scanner should be placed at the desired position over the document. Conventionally, operators positioned each document visually, Such positioning is troublesome to operators and is likely to result in inaccurate scanning results. To overcome this shortcoming, there has been proposed a document positioning scheme that permits an image sensor to detect a mark previously put on a document for the purpose of positioning, In this method, a mark having both the proper shape and color suitable for positioning of a document is previously put at an arbitrary position on a document. This mark defines an arbitrary area on the document to be scanned. When detecting this mark, the image scanner extracts information within the area defined by the mark and reads it as image signals. When such a mark is put on the upper left portion on the document, for example, information within an area of the size A4 is read as image signals.
A digital copying machine having a marker processing function has also been proposed. In the marker processing, a different process is executed for an area of a document encircled by a fluorescent color (marker) than that executed for an area not encircled. Japanese Patent Laid open No. 5-328099 discloses an image signal processing apparatus which allows an operator to designate any area of a plurality of areas marked with a fluorescent color and can then perform a different process for the designated area than that executed for the other areas.
No scheme has been proposed for positioning for a specific portion of an object to be sensed, unlike the aforementioned positioning of a document by the detention of a mark by an image scanner or by the marker processing function, in the field of image sensing technology, using a two-dimensionel CCD (Charge Coupled Device) solid state image sensing device. At present, the positioning of an object is performed on a visual basis by each operator. Such positioning is troublesome and is likely to lead to inaccurate positioning results. In particular, positioning of a specific portion of an object to be sensed is important to fix the image sensing range or area using a CCD solid state image sensing device.